/*
 *  ircd-hybrid: an advanced Internet Relay Chat Daemon(ircd).
 *  packet.c: Packet handlers.
 *
 *  Copyright (C) 2002 by the past and present ircd coders, and others.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 *  USA
 *
 *  $Id: packet.c 253 2006-02-11 14:00:43Z jon $
 */
#include "stdinc.h"
#include "tools.h"
#include "s_bsd.h"
#include "s_conf.h"
#include "s_serv.h"
#include "client.h"
#include "common.h"
#include "ircd.h"
#include "list.h"
#include "parse.h"
#include "fdlist.h"
#include "packet.h"
#include "irc_string.h"
#include "memory.h"
#include "hook.h"
#include "send.h"
#include "irc_getnameinfo.h"

#define READBUF_SIZE 16384

struct Callback *iorecv_cb = NULL;
struct Callback *iorecvctrl_cb = NULL;

static char readBuf[READBUF_SIZE];
static void client_dopacket(struct Client *, char *, size_t);

/* extract_one_line()
 *
 * inputs       - pointer to a dbuf queue
 *              - pointer to buffer to copy data to
 * output       - length of <buffer>
 * side effects - one line is copied and removed from the dbuf
 */
static int
extract_one_line(struct dbuf_queue *qptr, char *buffer)
{
	struct dbuf_block *block;
	int line_bytes = 0, empty_bytes = 0, phase = 0;
	unsigned int idx;

	char c;
	dlink_node *ptr;

	/*
	 * Phase 0: "empty" characters before the line
	 * Phase 1: copying the line
	 * Phase 2: "empty" characters after the line
	 *          (delete them as well and free some space in the dbuf)
	 *
	 * Empty characters are CR, LF and space (but, of course, not
	 * in the middle of a line). We try to remove as much of them as we can,
	 * since they simply eat server memory.
	 *
	 * --adx
	 */
	DLINK_FOREACH(ptr, qptr->blocks.head)
	{
		block = ptr->data;

		for(idx = 0; idx < block->size; idx++)
		{
			c = block->data[idx];
			if(IsEol(c) || (c == ' ' && phase != 1))
			{
				empty_bytes++;
				if(phase == 1)
					phase = 2;
			}
			else
				switch (phase)
				{
				case 0:
					phase = 1;
				case 1:
					if(line_bytes++ < IRCD_BUFSIZE - 2)
						*buffer++ = c;
					break;
				case 2:
					*buffer = '\0';
					dbuf_delete(qptr, line_bytes + empty_bytes);
					return IRCD_MIN(line_bytes, IRCD_BUFSIZE - 2);
				}
		}
	}

	/*
	 * Now, if we haven't reached phase 2, ignore all line bytes
	 * that we have read, since this is a partial line case.
	 */
	if(phase != 2)
		line_bytes = 0;
	else
		*buffer = '\0';

	/* Remove what is now unnecessary */
	dbuf_delete(qptr, line_bytes + empty_bytes);
	return IRCD_MIN(line_bytes, IRCD_BUFSIZE - 2);
}

/*
 * parse_client_queued - parse client queued messages
 */
static void
parse_client_queued(struct Client *client_p)
{
	int dolen = 0;
	int checkflood = 1;
	struct LocalUser *lclient_p = client_p->localClient;

	if(IsUnknown(client_p))
	{
		int i = 0;

		for(;;)
		{
			if(IsDefunct(client_p))
				return;

			/* rate unknown clients at MAX_FLOOD per loop */
			if(i >= MAX_FLOOD)
				break;

			dolen = extract_one_line(&lclient_p->buf_recvq, readBuf);
			if(dolen == 0)
				break;

			client_dopacket(client_p, readBuf, dolen);
			i++;

			/* if they've dropped out of the unknown state, break and move
			 * to the parsing for their appropriate status.  --fl
			 */
			if(!IsUnknown(client_p))
				break;
		}
	}

	if(IsServer(client_p) || IsConnecting(client_p) || IsHandshake(client_p))
	{
		while(1)
		{
			if(IsDefunct(client_p))
				return;
			if((dolen = extract_one_line(&lclient_p->buf_recvq, readBuf)) == 0)
				break;
			client_dopacket(client_p, readBuf, dolen);
		}
	}
	else if(IsClient(client_p))
	{
		if(ConfigFileEntry.no_oper_flood && (IsOper(client_p) || IsCanFlood(client_p)))
		{
			if(ConfigFileEntry.true_no_oper_flood)
				checkflood = -1;
			else
				checkflood = 0;
		}

		/*
		 * Handle flood protection here - if we exceed our flood limit on
		 * messages in this loop, we simply drop out of the loop prematurely.
		 *   -- adrian
		 */
		for(;;)
		{
			if(IsDefunct(client_p))
				break;

			/* This flood protection works as follows:
			 *
			 * A client is given allow_read lines to send to the server.  Every
			 * time a line is parsed, sent_parsed is increased.  sent_parsed
			 * is decreased by 1 every time flood_recalc is called.
			 *
			 * Thus a client can 'burst' allow_read lines to the server, any
			 * excess lines will be parsed one per flood_recalc() call.
			 *
			 * Therefore a client will be penalised more if they keep flooding,
			 * as sent_parsed will always hover around the allow_read limit
			 * and no 'bursts' will be permitted.
			 */
			if(checkflood > 0)
			{
				if(lclient_p->sent_parsed >= lclient_p->allow_read)
					break;
			}

			/* allow opers 4 times the amount of messages as users. why 4?
			 * why not. :) --fl_
			 */
			else if(lclient_p->sent_parsed >= (4 * lclient_p->allow_read) &&
				checkflood != -1)
				break;

			dolen = extract_one_line(&lclient_p->buf_recvq, readBuf);
			if(dolen == 0)
				break;

			client_dopacket(client_p, readBuf, dolen);
			lclient_p->sent_parsed++;
		}
	}
}

/* flood_endgrace()
 *
 * marks the end of the clients grace period
 */
void
flood_endgrace(struct Client *client_p)
{
	SetFloodDone(client_p);

	/* Drop their flood limit back down */
	client_p->localClient->allow_read = MAX_FLOOD;

	/* sent_parsed could be way over MAX_FLOOD but under MAX_FLOOD_BURST,
	 * so reset it.
	 */
	client_p->localClient->sent_parsed = 0;
}

/*
 * flood_recalc
 *
 * recalculate the number of allowed flood lines. this should be called
 * once a second on any given client. We then attempt to flush some data.
 */
void
flood_recalc(fde_t * fd, void *data)
{
	struct Client *client_p = data;
	struct LocalUser *lclient_p = client_p->localClient;

	/* allow a bursting client their allocation per second, allow
	 * a client whos flooding an extra 2 per second
	 */
	if(IsFloodDone(client_p))
		lclient_p->sent_parsed -= 2;
	else
		lclient_p->sent_parsed = 0;

	if(lclient_p->sent_parsed < 0)
		lclient_p->sent_parsed = 0;

	parse_client_queued(client_p);

	/* And now, try flushing .. */
	if(!IsDead(client_p))
	{
		/* and finally, reset the flood check */
		comm_setflush(fd, 1000, flood_recalc, client_p);
	}
}

/*
 * read_ctrl_packet - Read a 'packet' of data from a servlink control
 *                    link and process it.
 */
void
read_ctrl_packet(fde_t * fd, void *data)
{
	struct Client *server = data;
	struct LocalUser *lserver = server->localClient;
	struct SlinkRpl *reply;
	int length = 0;
	unsigned char tmp[2];
	unsigned char *len = tmp;
	struct SlinkRplDef *replydef;

	assert(lserver != NULL);

	reply = &lserver->slinkrpl;

	if(IsDefunct(server))
		return;

	if(!reply->command)
	{
		reply->gotdatalen = 0;
		reply->readdata = 0;
		reply->data = NULL;

		length = recv(fd->fd, tmp, 1, 0);

		if(length <= 0)
		{
			if((length == -1) && ignoreErrno(errno))
				goto nodata;
			dead_link_on_read(server, length);
			return;
		}
		reply->command = tmp[0];
	}

	for(replydef = slinkrpltab; replydef->handler; replydef++)
	{
		if(replydef->replyid == (unsigned int) reply->command)
			break;
	}

	/* we should be able to trust a local slink process...
	 * and if it sends an invalid command, that's a bug.. */
	assert(replydef->handler);

	if((replydef->flags & SLINKRPL_FLAG_DATA) && (reply->gotdatalen < 2))
	{
		/* we need a datalen u16 which we don't have yet... */
		length = recv(fd->fd, len, (2 - reply->gotdatalen), 0);
		if(length <= 0)
		{
			if((length == -1) && ignoreErrno(errno))
				goto nodata;
			dead_link_on_read(server, length);
			return;
		}

		if(reply->gotdatalen == 0)
		{
			reply->datalen = *len << 8;
			reply->gotdatalen++;
			length--;
			len++;
		}
		if(length && (reply->gotdatalen == 1))
		{
			reply->datalen |= *len;
			reply->gotdatalen++;
			if(reply->datalen > 0)
				reply->data = MyMalloc(reply->datalen);
		}

		if(reply->gotdatalen < 2)
			return;	/* wait for more data */
	}

	if(reply->readdata < reply->datalen)	/* try to get any remaining data */
	{
		length = recv(fd->fd, (reply->data + reply->readdata),
			      (reply->datalen - reply->readdata), 0);
		if(length <= 0)
		{
			if((length == -1) && ignoreErrno(errno))
				goto nodata;
			dead_link_on_read(server, length);
			return;
		}

		reply->readdata += length;
		if(reply->readdata < reply->datalen)
			return;	/* wait for more data */
	}

	execute_callback(iorecvctrl_cb, server, reply->command);

	/* we now have the command and any data, pass it off to the handler */
	(*replydef->handler) (reply->command, reply->datalen, reply->data, server);

	/* reset SlinkRpl */
	if(reply->datalen > 0)
		MyFree(reply->data);
	reply->command = 0;

	if(IsDead(server))
		return;

      nodata:
	/* If we get here, we need to register for another COMM_SELECT_READ */
	comm_setselect(fd, COMM_SELECT_READ, read_ctrl_packet, server, 0);
}

/*
 * iorecv_default - append a packet to the recvq dbuf
 */
void *
iorecv_default(va_list args)
{
	struct Client *client_p = va_arg(args, struct Client *);
	int length = va_arg(args, int);
	char *buf = va_arg(args, char *);

	dbuf_put(&client_p->localClient->buf_recvq, buf, length);
	return NULL;
}

/*
 * read_packet - Read a 'packet' of data from a connection and process it.
 */
void
read_packet(fde_t * fd, void *data)
{
	struct Client *client_p = data;
	int length = 0;

	if(IsDefunct(client_p))
		return;

	/*
	 * Read some data. We *used to* do anti-flood protection here, but
	 * I personally think it makes the code too hairy to make sane.
	 *     -- adrian
	 */
	do
	{
#ifdef HAVE_LIBCRYPTO
		if(fd->ssl)
		{
			length = SSL_read(fd->ssl, readBuf, READBUF_SIZE);

			/* translate openssl error codes, sigh */
			if(length < 0)
				switch (SSL_get_error(fd->ssl, length))
				{
				case SSL_ERROR_WANT_WRITE:
					fd->flags.pending_read = 1;
					SetSendqBlocked(client_p);
					comm_setselect(fd, COMM_SELECT_WRITE,
						       (PF *) sendq_unblocked, client_p, 0);
					return;

				case SSL_ERROR_WANT_READ:
					errno = EWOULDBLOCK;

				case SSL_ERROR_SYSCALL:
					break;

				case SSL_ERROR_SSL:
					if(errno == EAGAIN)
						break;

				default:
					length = errno = 0;
				}
		}
		else
#endif
		{
			length = recv(fd->fd, readBuf, READBUF_SIZE, 0);
#ifdef _WIN32
			if(length < 0)
				errno = WSAGetLastError();
#endif
		}

		if(length <= 0)
		{
			/*
			 * If true, then we can recover from this error.  Just jump out of
			 * the loop and re-register a new io-request.
			 */
			if(length < 0 && ignoreErrno(errno))
				break;

			dead_link_on_read(client_p, length);
			return;
		}

		execute_callback(iorecv_cb, client_p, length, readBuf);

		if(client_p->lasttime < CurrentTime)
			client_p->lasttime = CurrentTime;
		if(client_p->lasttime > client_p->since)
			client_p->since = CurrentTime;
		ClearPingSent(client_p);

		/* Attempt to parse what we have */
		parse_client_queued(client_p);

		if(IsDefunct(client_p))
			return;

		/* Check to make sure we're not flooding */
		/* TBD - ConfigFileEntry.client_flood should be a size_t */
		if(!(IsServer(client_p) || IsHandshake(client_p) || IsConnecting(client_p))
		   && (dbuf_length(&client_p->localClient->buf_recvq) >
		       (unsigned int) ConfigFileEntry.client_flood))
		{
			if(!(ConfigFileEntry.no_oper_flood && IsOper(client_p)))
			{
				exit_client(client_p, client_p, "Excess Flood");
				return;
			}
		}
	}
#ifdef HAVE_LIBCRYPTO
	while(length == sizeof(readBuf) || fd->ssl);
#else
	while(length == sizeof(readBuf));
#endif

	/* If we get here, we need to register for another COMM_SELECT_READ */
	comm_setselect(fd, COMM_SELECT_READ, read_packet, client_p, 0);
}

/*
 * client_dopacket - copy packet to client buf and parse it
 *      client_p - pointer to client structure for which the buffer data
 *             applies.
 *      buffer - pointr to the buffer containing the newly read data
 *      length - number of valid bytes of data in the buffer
 *
 * Note:
 *      It is implicitly assumed that dopacket is called only
 *      with client_p of "local" variation, which contains all the
 *      necessary fields (buffer etc..)
 */
static void
client_dopacket(struct Client *client_p, char *buffer, size_t length)
{
	/* 
	 * Update messages received
	 */
	++me.localClient->recv.messages;
	++client_p->localClient->recv.messages;

	/* 
	 * Update bytes received
	 */
	client_p->localClient->recv.bytes += length;
	me.localClient->recv.bytes += length;

	parse(client_p, buffer, buffer + length);
}
